/*
 *    md5.c
 *
 *    Implements    the  MD5 Message-Digest Algorithm as specified in
 *    RFC  1321.  This  implementation  is a simple one, in that it
 *    needs  every  input  byte  to  be  buffered  before doing any
 *    calculations.  I  do  not  expect  this  file  to be used for
 *    general  purpose  MD5'ing  of large amounts of data, only for
 *    generating hashed passwords from limited input.
 *
 *    Sverre H. Huseby <sverrehu@online.no>
 *
 *    Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
 *    Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *      src/common/md5.c
 */

#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif

#include "common/md5.h"


/*
 *    PRIVATE FUNCTIONS
 */


/*
 *    The returned array is allocated using malloc.  the caller should free it
 *    when it is no longer needed.
 */
static uint8 *
createPaddedCopyWithLength(const uint8 *b, uint32 *l)
{
    uint8       *ret;
    uint32        q;
    uint32        len,
                newLen448;
    uint32        len_high,
                len_low;        /* 64-bit value split into 32-bit sections */

    len = ((b == NULL) ? 0 : *l);
    newLen448 = len + 64 - (len % 64) - 8;
    if (newLen448 <= len)
        newLen448 += 64;

    *l = newLen448 + 8;
    if ((ret = (uint8 *) malloc(sizeof(uint8) * *l)) == NULL)
        return NULL;

    if (b != NULL)
        memcpy(ret, b, sizeof(uint8) * len);

    /* pad */
    ret[len] = 0x80;
    for (q = len + 1; q < newLen448; q++)
        ret[q] = 0x00;

    /* append length as a 64 bit bitcount */
    len_low = len;
    /* split into two 32-bit values */
    /* we only look at the bottom 32-bits */
    len_high = len >> 29;
    len_low <<= 3;
    q = newLen448;
    ret[q++] = (len_low & 0xff);
    len_low >>= 8;
    ret[q++] = (len_low & 0xff);
    len_low >>= 8;
    ret[q++] = (len_low & 0xff);
    len_low >>= 8;
    ret[q++] = (len_low & 0xff);
    ret[q++] = (len_high & 0xff);
    len_high >>= 8;
    ret[q++] = (len_high & 0xff);
    len_high >>= 8;
    ret[q++] = (len_high & 0xff);
    len_high >>= 8;
    ret[q] = (len_high & 0xff);

    return ret;
}

#define F(x, y, z) (((x) & (y)) | (~(x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & ~(z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | ~(z)))
#define ROT_LEFT(x, n) (((x) << (n)) | ((x) >> (32 - (n))))

static void
doTheRounds(uint32 X[16], uint32 state[4])
{
    uint32        a,
                b,
                c,
                d;

    a = state[0];
    b = state[1];
    c = state[2];
    d = state[3];

    /* round 1 */
    a = b + ROT_LEFT((a + F(b, c, d) + X[0] + 0xd76aa478), 7);    /* 1 */
    d = a + ROT_LEFT((d + F(a, b, c) + X[1] + 0xe8c7b756), 12); /* 2 */
    c = d + ROT_LEFT((c + F(d, a, b) + X[2] + 0x242070db), 17); /* 3 */
    b = c + ROT_LEFT((b + F(c, d, a) + X[3] + 0xc1bdceee), 22); /* 4 */
    a = b + ROT_LEFT((a + F(b, c, d) + X[4] + 0xf57c0faf), 7);    /* 5 */
    d = a + ROT_LEFT((d + F(a, b, c) + X[5] + 0x4787c62a), 12); /* 6 */
    c = d + ROT_LEFT((c + F(d, a, b) + X[6] + 0xa8304613), 17); /* 7 */
    b = c + ROT_LEFT((b + F(c, d, a) + X[7] + 0xfd469501), 22); /* 8 */
    a = b + ROT_LEFT((a + F(b, c, d) + X[8] + 0x698098d8), 7);    /* 9 */
    d = a + ROT_LEFT((d + F(a, b, c) + X[9] + 0x8b44f7af), 12); /* 10 */
    c = d + ROT_LEFT((c + F(d, a, b) + X[10] + 0xffff5bb1), 17);    /* 11 */
    b = c + ROT_LEFT((b + F(c, d, a) + X[11] + 0x895cd7be), 22);    /* 12 */
    a = b + ROT_LEFT((a + F(b, c, d) + X[12] + 0x6b901122), 7); /* 13 */
    d = a + ROT_LEFT((d + F(a, b, c) + X[13] + 0xfd987193), 12);    /* 14 */
    c = d + ROT_LEFT((c + F(d, a, b) + X[14] + 0xa679438e), 17);    /* 15 */
    b = c + ROT_LEFT((b + F(c, d, a) + X[15] + 0x49b40821), 22);    /* 16 */

    /* round 2 */
    a = b + ROT_LEFT((a + G(b, c, d) + X[1] + 0xf61e2562), 5);    /* 17 */
    d = a + ROT_LEFT((d + G(a, b, c) + X[6] + 0xc040b340), 9);    /* 18 */
    c = d + ROT_LEFT((c + G(d, a, b) + X[11] + 0x265e5a51), 14);    /* 19 */
    b = c + ROT_LEFT((b + G(c, d, a) + X[0] + 0xe9b6c7aa), 20); /* 20 */
    a = b + ROT_LEFT((a + G(b, c, d) + X[5] + 0xd62f105d), 5);    /* 21 */
    d = a + ROT_LEFT((d + G(a, b, c) + X[10] + 0x02441453), 9); /* 22 */
    c = d + ROT_LEFT((c + G(d, a, b) + X[15] + 0xd8a1e681), 14);    /* 23 */
    b = c + ROT_LEFT((b + G(c, d, a) + X[4] + 0xe7d3fbc8), 20); /* 24 */
    a = b + ROT_LEFT((a + G(b, c, d) + X[9] + 0x21e1cde6), 5);    /* 25 */
    d = a + ROT_LEFT((d + G(a, b, c) + X[14] + 0xc33707d6), 9); /* 26 */
    c = d + ROT_LEFT((c + G(d, a, b) + X[3] + 0xf4d50d87), 14); /* 27 */
    b = c + ROT_LEFT((b + G(c, d, a) + X[8] + 0x455a14ed), 20); /* 28 */
    a = b + ROT_LEFT((a + G(b, c, d) + X[13] + 0xa9e3e905), 5); /* 29 */
    d = a + ROT_LEFT((d + G(a, b, c) + X[2] + 0xfcefa3f8), 9);    /* 30 */
    c = d + ROT_LEFT((c + G(d, a, b) + X[7] + 0x676f02d9), 14); /* 31 */
    b = c + ROT_LEFT((b + G(c, d, a) + X[12] + 0x8d2a4c8a), 20);    /* 32 */

    /* round 3 */
    a = b + ROT_LEFT((a + H(b, c, d) + X[5] + 0xfffa3942), 4);    /* 33 */
    d = a + ROT_LEFT((d + H(a, b, c) + X[8] + 0x8771f681), 11); /* 34 */
    c = d + ROT_LEFT((c + H(d, a, b) + X[11] + 0x6d9d6122), 16);    /* 35 */
    b = c + ROT_LEFT((b + H(c, d, a) + X[14] + 0xfde5380c), 23);    /* 36 */
    a = b + ROT_LEFT((a + H(b, c, d) + X[1] + 0xa4beea44), 4);    /* 37 */
    d = a + ROT_LEFT((d + H(a, b, c) + X[4] + 0x4bdecfa9), 11); /* 38 */
    c = d + ROT_LEFT((c + H(d, a, b) + X[7] + 0xf6bb4b60), 16); /* 39 */
    b = c + ROT_LEFT((b + H(c, d, a) + X[10] + 0xbebfbc70), 23);    /* 40 */
    a = b + ROT_LEFT((a + H(b, c, d) + X[13] + 0x289b7ec6), 4); /* 41 */
    d = a + ROT_LEFT((d + H(a, b, c) + X[0] + 0xeaa127fa), 11); /* 42 */
    c = d + ROT_LEFT((c + H(d, a, b) + X[3] + 0xd4ef3085), 16); /* 43 */
    b = c + ROT_LEFT((b + H(c, d, a) + X[6] + 0x04881d05), 23); /* 44 */
    a = b + ROT_LEFT((a + H(b, c, d) + X[9] + 0xd9d4d039), 4);    /* 45 */
    d = a + ROT_LEFT((d + H(a, b, c) + X[12] + 0xe6db99e5), 11);    /* 46 */
    c = d + ROT_LEFT((c + H(d, a, b) + X[15] + 0x1fa27cf8), 16);    /* 47 */
    b = c + ROT_LEFT((b + H(c, d, a) + X[2] + 0xc4ac5665), 23); /* 48 */

    /* round 4 */
    a = b + ROT_LEFT((a + I(b, c, d) + X[0] + 0xf4292244), 6);    /* 49 */
    d = a + ROT_LEFT((d + I(a, b, c) + X[7] + 0x432aff97), 10); /* 50 */
    c = d + ROT_LEFT((c + I(d, a, b) + X[14] + 0xab9423a7), 15);    /* 51 */
    b = c + ROT_LEFT((b + I(c, d, a) + X[5] + 0xfc93a039), 21); /* 52 */
    a = b + ROT_LEFT((a + I(b, c, d) + X[12] + 0x655b59c3), 6); /* 53 */
    d = a + ROT_LEFT((d + I(a, b, c) + X[3] + 0x8f0ccc92), 10); /* 54 */
    c = d + ROT_LEFT((c + I(d, a, b) + X[10] + 0xffeff47d), 15);    /* 55 */
    b = c + ROT_LEFT((b + I(c, d, a) + X[1] + 0x85845dd1), 21); /* 56 */
    a = b + ROT_LEFT((a + I(b, c, d) + X[8] + 0x6fa87e4f), 6);    /* 57 */
    d = a + ROT_LEFT((d + I(a, b, c) + X[15] + 0xfe2ce6e0), 10);    /* 58 */
    c = d + ROT_LEFT((c + I(d, a, b) + X[6] + 0xa3014314), 15); /* 59 */
    b = c + ROT_LEFT((b + I(c, d, a) + X[13] + 0x4e0811a1), 21);    /* 60 */
    a = b + ROT_LEFT((a + I(b, c, d) + X[4] + 0xf7537e82), 6);    /* 61 */
    d = a + ROT_LEFT((d + I(a, b, c) + X[11] + 0xbd3af235), 10);    /* 62 */
    c = d + ROT_LEFT((c + I(d, a, b) + X[2] + 0x2ad7d2bb), 15); /* 63 */
    b = c + ROT_LEFT((b + I(c, d, a) + X[9] + 0xeb86d391), 21); /* 64 */

    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
}

static int
calculateDigestFromBuffer(const uint8 *b, uint32 len, uint8 sum[16])
{
    register uint32 i,
                j,
                k,
                newI;
    uint32        l;
    uint8       *input;
    register uint32 *wbp;
    uint32        workBuff[16],
                state[4];

    l = len;

    state[0] = 0x67452301;
    state[1] = 0xEFCDAB89;
    state[2] = 0x98BADCFE;
    state[3] = 0x10325476;

    if ((input = createPaddedCopyWithLength(b, &l)) == NULL)
        return 0;

    for (i = 0;;)
    {
        if ((newI = i + 16 * 4) > l)
            break;
        k = i + 3;
        for (j = 0; j < 16; j++)
        {
            wbp = (workBuff + j);
            *wbp = input[k--];
            *wbp <<= 8;
            *wbp |= input[k--];
            *wbp <<= 8;
            *wbp |= input[k--];
            *wbp <<= 8;
            *wbp |= input[k];
            k += 7;
        }
        doTheRounds(workBuff, state);
        i = newI;
    }
    free(input);

    j = 0;
    for (i = 0; i < 4; i++)
    {
        k = state[i];
        sum[j++] = (k & 0xff);
        k >>= 8;
        sum[j++] = (k & 0xff);
        k >>= 8;
        sum[j++] = (k & 0xff);
        k >>= 8;
        sum[j++] = (k & 0xff);
    }
    return 1;
}

static void
bytesToHex(uint8 b[16], char *s)
{
    static const char *hex = "0123456789abcdef";
    int            q,
                w;

    for (q = 0, w = 0; q < 16; q++)
    {
        s[w++] = hex[(b[q] >> 4) & 0x0F];
        s[w++] = hex[b[q] & 0x0F];
    }
    s[w] = '\0';
}

/*
 *    PUBLIC FUNCTIONS
 */

/*
 *    pg_md5_hash
 *
 *    Calculates the MD5 sum of the bytes in a buffer.
 *
 *    SYNOPSIS      #include "md5.h"
 *                  int pg_md5_hash(const void *buff, size_t len, char *hexsum)
 *
 *    INPUT          buff      the buffer containing the bytes that you want
 *                          the MD5 sum of.
 *                  len      number of bytes in the buffer.
 *
 *    OUTPUT          hexsum  the MD5 sum as a '\0'-terminated string of
 *                          hexadecimal digits.  an MD5 sum is 16 bytes long.
 *                          each byte is represented by two heaxadecimal
 *                          characters.  you thus need to provide an array
 *                          of 33 characters, including the trailing '\0'.
 *
 *    RETURNS          false on failure (out of memory for internal buffers) or
 *                  true on success.
 *
 *    STANDARDS      MD5 is described in RFC 1321.
 *
 *    AUTHOR          Sverre H. Huseby <sverrehu@online.no>
 *
 */
bool
pg_md5_hash(const void *buff, size_t len, char *hexsum)
{
    uint8        sum[16];

    if (!calculateDigestFromBuffer(buff, len, sum))
        return false;

    bytesToHex(sum, hexsum);
    return true;
}

bool
pg_md5_binary(const void *buff, size_t len, void *outbuf)
{
    if (!calculateDigestFromBuffer(buff, len, outbuf))
        return false;
    return true;
}


/*
 * Computes MD5 checksum of "passwd" (a null-terminated string) followed
 * by "salt" (which need not be null-terminated).
 *
 * Output format is "md5" followed by a 32-hex-digit MD5 checksum.
 * Hence, the output buffer "buf" must be at least 36 bytes long.
 *
 * Returns TRUE if okay, FALSE on error (out of memory).
 */
bool
pg_md5_encrypt(const char *passwd, const char *salt, size_t salt_len,
               char *buf)
{
    size_t        passwd_len = strlen(passwd);

    /* +1 here is just to avoid risk of unportable malloc(0) */
    char       *crypt_buf = malloc(passwd_len + salt_len + 1);
    bool        ret;

    if (!crypt_buf)
        return false;

    /*
     * Place salt at the end because it may be known by users trying to crack
     * the MD5 output.
     */
    memcpy(crypt_buf, passwd, passwd_len);
    memcpy(crypt_buf + passwd_len, salt, salt_len);

    strcpy(buf, "md5");
    ret = pg_md5_hash(crypt_buf, passwd_len + salt_len, buf + 3);

    free(crypt_buf);

    return ret;
}
